gnu: python-jupyter-kernel-mgmt: Update to 0.5.1 and disable tests.

* gnu/packages/jupyter.scm (python-jupyter-kernel-mgmt): Update to 0.5.1.
[arguments]: New field.
[propagated-inputs]: Add python-tornado.
[native-inputs]: Remove python-mock.  Add python-async-generator and
python-pytest-asyncio.

gnu/packages/jupyter.scm

@@ -82,23 +82,40 @@ protocol} to be used by both clients and kernels.")
 (define-public python-jupyter-kernel-mgmt
   (package
     (name "python-jupyter-kernel-mgmt")
-    (version "0.4.0")
+    (version "0.5.1")
     (source (origin
               (method url-fetch)
               (uri (pypi-uri "jupyter_kernel_mgmt" version))
               (sha256
                (base32
-                "0i7a78dn89ca8h0a42giyxwcmk6y4wrdr7q8h2ax9vybb84c795q"))))
+                "0977ixfi1pzjgy84hl0zycg4wpllmid98fhzcpy0lxd322w4sl7x"))))
     (build-system python-build-system)
+    (arguments
+     (list
+      ;; There are 8 test failures, most of them in 'test_client_loop.py'
+      ;; (see: https://github.com/takluyver/jupyter_kernel_mgmt/issues/48).
+      #:tests? #f
+      #:phases
+      #~(modify-phases %standard-phases
+          (replace 'check
+            (lambda* (#:key tests? #:allow-other-keys)
+              (when tests?
+                (setenv "HOME" "/tmp")
+                (invoke "pytest" "-vv" "jupyter_kernel_mgmt")))))))
     (propagated-inputs
      (list python-dateutil
            python-entrypoints
            python-jupyter-core
            python-jupyter-protocol
            python-pyzmq
+           python-tornado
            python-traitlets))
     (native-inputs
-     (list python-ipykernel python-ipython python-mock python-pytest))
+     (list python-async-generator
+           python-ipykernel
+           python-ipython
+           python-pytest
+           python-pytest-asyncio))
     (home-page "https://jupyter.org")
     (synopsis "Discover, launch, and communicate with Jupyter kernels")
     (description